/*$$
 * Copyright (c) 1999, Trustees of the University of Chicago
 * All rights reserved.
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 * or without modification, are permitted provided that the following 
 * conditions are met:
 *
 *	 Redistributions of source code must retain the above copyright notice,
 *	 this list of conditions and the following disclaimer.
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 *
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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package uchicago.src.sim.space;


import java.util.ArrayList;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;


/**
 * A grid cell whose occupants are stored as if in a bag without order.
 * Removing objects from this type of cell will be faster than from an
 * ordered cell.
 *
 * @version $Revision: 1.5 $ $Date: 2004/11/03 19:50:58 $
 */

public class BagCell implements Cell {

    private HashSet elements = new HashSet();

    /**
     * Returns true if this BagCell contains the specified object.
     */
    public boolean contains(Object o) {
        return elements.contains(o);
    }

    // Cell interface

    /**
     * Returns the number of objects in this cell.
     */
    public int size() {
        return elements.size();
    }

    /**
     * Clears all the objects from this cell.
     */
    public void clear() {
        elements.clear();
    }
  
    /**
     * Adds an object to this cell.
     */
    public void add(Object o) {
        elements.add(o);
    }

    /**
     * Returns a List of the objects contained in this cell.
     */
    public List getList() {
        return new ArrayList(elements);
    }

    /**
     * Returns an Iterator of the objects contained in this cell.
     */
    public Iterator iterator() {
        return elements.iterator();
    }
  
    /**
     * Removes the specified object from this cell.
     */
    public void remove(Object o) {
        elements.remove(o);
    }
}
